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United States Department of Agriculture

Agricultural Research Service

Title: Precipitation Variations in Central Oklahoma and in the Great Plains

Authors
item Garbrecht, Jurgen
item Schneider, Jeanne

Submitted to: Grazinglands Research Laboratory Miscellaneous Publication
Publication Type: Research Notes
Publication Acceptance Date: October 12, 2000
Publication Date: October 12, 2000

Interpretive Summary: Annual precipitation for a city or county generally varies from year to year. Sometimes ten or more years will have mostly above or below average precipitation. Such variations in precipitation are natural occurrences and, at different times, have contributed to the prosperity or hardship of farmers and ranchers. Variations in precipitation that last ten or more years may have serious consequences for dry-land agriculture, long-term irrigation water needs, and water conservation strategies. The objective of this study was to identify recent precipitation changes in the Great Plains, and to quantify these changes on a regional basis. The study revealed that many regions in the Central and Southern Great Plains experienced mostly above average precipitation conditions over the last two decades of the 20th century (1980-1999). The 20-year precipitation increase was primarily the result of a reduction in the number of dry years, as opposed to an increase in the amount of precipitation during wet years. The finding of this study, has immediate implications for practical agricultural applications that deal with long-term planning, management and utilization of water.

Technical Abstract: Annual precipitation varies from year to year. Sometimes a sequence of ten or more years will have mostly above or below average precipitation. Such variations are natural occurrences and may have serious consequences for dry-land agriculture, long-term irrigation water needs, and water conservation strategies. The objective of this study was to identify recent precipitation changes in the Great Plains, and to quantify these changes on a regional basis. The purpose for conducting this study was to encourage the consideration of multi-year precipitation variations in practical agricultural applications. The study revealed that many regions in the Central and Southern Great Plains experienced mostly above average precipitation conditions over the last two decades of the 20th century (1980-1999). The 20-year precipitation increase was primarily the result of a reduction in the number of dry years, as opposed to an increase in the eamount of precipitation during wet years. On a seasonal basis, most of th precipitation increase occurred during late spring, early summer and autumn months. The broad and far reaching economic and societal consequences of decade-long precipitation variations requires that variations in precipitation be identified early. With early identification adaptive and mitigating strategies may be developed, opportunities exploited, and policies and investments made to ensure a secure water supply and a responsive and competitive economy. This study provides an order of magnitude and a geographic extent for changes in annual precipitation in the recent past.

Last Modified: 4/23/2014
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